A femtocell is a small access base station designed to improve wireless reception inside a residential or small business environment. End users may purchase femtocells associated with a particular service provider, and the femtocell may only use the licensed frequency of the particular service provider. The femtocell connects to the service provider's network and allows the service provider to extend service coverage of existing MacroCells indoors, especially where access would otherwise be limited or unavailable. A mobile phone call initiated in a home or office equipped with a femtocell would start at the mobile handset, be sent to the femtocell, and go from the femtocell via a backhaul, i.e., high-speed internet connection, to the wireless network.
When femtocells are added to a standard radio base station cellular coverage pattern, i.e., macro cell, there may be too many femtocells for each femtocell to have its own unique PN Offset, or identifying code, within the macro cell coverage. Disadvantageously, since the pseudo noise (PN) offsets are not unique, a particular mobile phone is likely to find other femtocells as well as its own femtocells when looking in a General Neighbor List.
When the mobile phone finds a femtocell to which it has no access, and stays in that location, it may end up in a constant idle hand-off loop, where it constantly finds the restricted access femtocell, and is redirected. Disadvantageously, the mobile phone may not receive service. Also disadvantageously, when the femtocell is located very close to the radio base station on a dedicated frequency, mobile phones that are allowed to use the femtocell may not perform an idle hand-off to the femtocell, since the radio base station's power/noise ratio overshadows that of the femtocell.